1) Field of the Invention
The present invention relates to fire protection for high-risk facilities such as electrical power plants and electrical sub-stations, and more particularly, to a comprehensive passive fire protection system to prevent fire damage from burning power cables from spreading between adjacent power cables, control cables, equipment and rooms of utility facilities.
2) Description of Related Art
Fire protection for power facilities is a critical component of their construction given the tendency for fires to occur at such facilities. A fire at an electrical sub-station can cause substantial damage to equipment, cause outage time to a service area, and cost millions of dollars to repair if proper fire prevention techniques are not used. Unfortunately, the currently used techniques and materials to prevent such fire damage are inadequate for intended protection, inadequate to protect against the severity and duration of the fire, improperly installed, or are completely unqualified designs that can accelerate the spread of a fire. For example, inspections of electrical sub-station facilities has revealed unqualified or missing fire penetration seals (“firestops”) around power and control cables passing between floors. This degrades the fire rating of the floor separating, for example, a switchgear room from a basement where the majority of the power and control cables are routed. Degraded fire barriers can allow passage of fire and smoke through the floor openings, creating problems for the operation of switchgear, or even the total loss of a sub-station. As smoke can travel up to 420 feet per minute, proper containment is essential to effectively combat a fire and maintain operation of the facility. Further, it has been observed that because specific standards mandated for passive fire protection systems have been ignored, combustible materials, such as cardboard and rags, have been used to seal openings between floors, which can have devastating consequences.
The vast majority of fire protection systems are designed to be installed from above the floor. In sub-station basements, “above the floor” typically means inside a switch gear or bus cabinet. This can create a substantial design flaw in the protection depending on the type of floor. For example, when installing an “above the floor” seal in a hollow core concrete floor, typically accomplished with small amounts of mineral wool and caulk jammed around the cable or pipe, there is no protection which extends into the flooring to seal off the large openings formed in the flooring itself. This allows the fire and smoke to spread through the flooring and possibly causing the floor to fail or find an alternative exit into the room above.
Further, effective passive fire protection requires unique designs depending on the type of flooring. Different passive fire protection seal designs are often required for different floor types, including: hollow core floor, 3 inch concrete slab, 6 to 9 inch concrete slab, concrete on metal pan deck, or metal floor. The prior art does not effectively give consideration to adapting qualified passive fire protection designs for many different types of flooring. Because each type of floor has its own design challenges, failure to use a qualified protection method can substantially degrade the fire rating of the floor and eliminate any inherent protection therein.
In addition to maintaining the effective fire rating of the flooring, it is important to anticipate and protect against overheating and explosions of connections between power cables. When a cable joint explodes, fire and molten metal from the cable fault typically knock out adjacent cables, shutting down other power circuits. Further, burning power cables have damaged control cables routed above power cables, degrading ability to operate the sub-station. The prior art and current fire protection techniques fail to properly and adequately address these problems.
Aside from openings in flooring for cabling and the like, a typical sub-station often has a steel hatchway cover between floors. For example, such a hatchway cover is used to close an access way between the basement and the sub-station battery backup power room. It has been observed that heat radiating through a closed steel hatchway cover resulting from a basement fire at a sub-station melted the battery packs in the room above. This resulted in failure of the sub-station backup power. Damage to the facilities backup power system prevented operation of switchgear, leading to a larger power outage. Thus, there is a need to protect such hatchways from radiating heat that may damage equipment in adjacent rooms.
Accordingly, it is an object of the present invention to provide a comprehensive passive fire protection system for high-risk buildings such as power facilities.
It is an object of the present invention to provide fireproof seal designs for closing cable penetration openings that can be efficiently installed from underneath the floor to contain fire and smoke within a compartment.
It is an object of the present invention to provide specific passive fire protection designs for specific types of flooring to maintain the fire rating of the flooring.
It is an object of the present invention to provide a passive fire protection system that includes fire resistant wraps for power cable joints so that an exploding power cable joint has reduced capability of damaging adjacent power cables.
It is an object of the present invention to provide a passive fire protection system that includes a fire barrier between control cables and power cables to protect the control cables from exploding and burning power cables so that operations of the facility can be maintained.
It is an object of the present invention to provide a passive fire protection system that includes radiant heat shielding for hatchways so that radiant heat passing through hatchway covers is prevented from damaging equipment in adjacent rooms.